Availability and reliability analysis of integrated reverse osmosis - forward osmosis desalination network

The hybrid desalination of reverse osmosis (RO) with forward osmosis (FO) is an innovative technology for freshwater production worldwide, which provides many advantages such as RO fouling and scaling, recovery of the energy of RO brine, minimizing the power consumption and minimizing the use of chemicals required for conventional pretreatment steps. For this reason, breakdowns, blockage of the membrane, pressure losses and preventive maintenance have to be minimized in duration and frequency to ensure the maximum availability and indeed improving the availability or reliability of the system leads objectively to the reduction of operating costs. In this study, hybrid fault tree analysis method based fuzzy set theory was considered to evaluate the availability and reliability of the integrated RO-FO desalination system. For assessing availability, the system was divided into four subsystems such as seawater intake pump, pressurization stage, FO stage and RO stage. The data were collected from reliability data bank and probabilities estimated by considering the fuzzy set theory, wherever detailed data were not available. The overall unavailability of the hybrid system was 0.0156.